Manufacture of sulphuric acid



Patented Nov. 192 6.?

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the contact process,

My invention relates to the manufacture sulphuric acid by the contact process and it comprises a processywhereby sulphuric dioxide and oxygen are heated and passed over a catalytic mass of alumina to, form sulphur trioxide;

In the manufacture 'of sulphuric acid by it; is necessary to oxidize sulphur dioxide to sulphur trioxide, this heingaccomplished by passing a mixture of sulphur dioxide and a r or oxygen overa contact catalyst under the influence of heat.

Although there have been numerous contact materials proposed for this purpose the only ones which have proven successful ona commercia-l The former is not catalyst but it has the advantage of being comparatively insensitive to poisoning a- 'ditions. air or'oxygen and sulphur dioxideand varytion; adisadvantage in the use of ferric oxide is, the fact that it is usually necessary to pass the residual and unconverted gases from this, catalyst over platinum in order.

to completion.-

that the reaction may go Platinum isthe more effective by far, but it has the disadvantage that it is very expensive and that an exceedingly'pu-re supply of sulphur dioxide is necessary. The slightest traces of arsenic, antimony selenium and similar substances, which are often present in su lphurous gases, will act as poisons tend:

ingto be adsorbed as a tenacious layer upon the active surface and greatly impairing itsfor this purpose a natural occurring hydrated alumina known as diaspore, which is usually represented as AI O ILQ By contacting sulphur dioxide gas-and air: or

oxygen with this material under the in fiuence of heat, I have been able to obtain yields of sulphur trioxide which compare favorably with those resulting of platinum under substantiallysimilar con- I may use varying proportions of ingdeg'rees of heat, but I prefer to use an excess of oxygen in the gaseous mixture sup-.

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trioxide.

scale are iron oxide and platinum} a particularly eflicient such treatment is not by the oxidation of sulphur dioxide, from the use.

A. CORPORATION OF TEXAS.

" i mmaon' filed December 4, 1924. Serial No. 753,800.

to the catalyst and to carryout thereaction at temperatures between 450 and 550 C. in order to obtain the highest 0s sible rate of conversion and yield of sulp ur As the cost of an aluminacont'act material is normal, it is obviovsthat there is an enormous economic advantage to be gained by its substitution for platinum and ata comparatively small sacrifice in efficiency.

important feature of the use of alumina and more particularly the mineral,

diaspore, isthe comparative-lack of sue-- ceptibilit to the usual catalyst poisons.

While s'u phur dioxide gases which are to be contacted with platinum must be put through an elaborate system of purification and drying in order to avoid destruction of the. essential qualities of the contact mass, necessary when .the alumina catalyst is employed. There is no adsoigtion of the arsenic or related compoun s nor is there any appreciable reaction with thesulphurous ases which would cause a change in compos tion or substance or a loss inactivity. Therefore, although the ex- I tremely'lovv initial cost m1 htallow a frequent renewal and substitution of fresh ma-I terial, such change is not necessary in Vl6W of the long life and high state of efficiency retained under operating-conditions.

. Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and 'scopethereof, and therefore, only such limitations should'be imposed as are indioated in the appended claims.

What ll claim is: 1. The process .of manufacturing sulphur trioxide which comprises passing sulphur dioxide and oxygen over heateddiaspore.

The process of manufacturing sulphur trioxldewlnch comprises passing a gaseous mixture containing sulphur dioxide and air in contact with diasporeiunder the influence of; heat.

"3 In the manufacture of sulphur trioxide the step that consists in carrying onthe oxidation in the presence of d'iaspore as a catalyst.

In Witness whereof I have hereunto set my hand 22nd day of November, 1924. a

; not a. vvoneorr. 

